1. Field of the Invention
The present invention is related to a magnetic disc cartridge having a magnetic disc accommodated therein. More particularly, it is related to a hard case structure having a groove for engagement with a shutter actuation pin.
2. Description of the Related Art
The use of a magnetic disc as a memory medium is widely known for a variety of applications, such as a memory unit in an electronic computer. Such a disc is usually accommodated in a casing to enable it to be optionally loaded in a disc drive apparatus or removed therefrom for storage. Two types of casings are available: one, a flexible jacket made of, for example, a vinyl chloride and generally known as a floppy disc; and another, a hard case structure rotatably accommodating the magnetic disc and generally known as a magnetic disc cartridge.
In the known magnetic disc cartridge, the hard case is constituted by a pair of upper and lower hard case members having identical profiles, which are superimposed, one on the other, and joined together. The case is provided with an aperture to enable access of a read-write head to the magnetic disc and a shutter to selectively cover the aperture. The shutter is operated by a shutter actuation pin arranged in the disc drive apparatus, which opens the aperture when the cartridge is loaded in the apparatus. The shutter actuation pin finally comes to rest in a groove provided in the peripheral surface of the cartridge case across the adjoining surfaces of the two case members to lock the shutter in the open position. However, a problem can arise in such a magnetic disc cartridge when the cartridge is being loaded in the disc drive apparatus, in that the shutter actuation pin will catch on the case at the adjoining surfaces of the two case members if the two case members were not exactly superposed during assembly of the cartridge, and the shutter actuation pin may then ride on the lower case member projected or displaced from the upper case member and will not be able to attain its correct position, with the result that the pin will exert pressure on the case and cause the cartridge to bend.